A mobile streaming media technology based on a hyper text transfer protocol (Hyper Text Transfer Protocol, HTTP) is widely recognized and supported because of the features of simple deployment, easy achievement of a terminal and the like. The manner of downloading a media file based on the HTTP protocol may be any one of an adaptive streaming Adaptive Streaming mode or a progressive download Progressive Download mode.
The Adaptive Streaming mode refers to that a media file is divided into multiple fragments at a server, then each media file fragment is transmitted in a media stream form through the HTTP protocol, and the chip rate may be changed in a media play process according to network bandwidth resources, for enabling a user to view a smooth video. The network will retain certain bandwidth resources for downloading the media file. In the case of sufficient bandwidth resources, the user will select uniform resource locators (Uniform Resource Locators, URLs) of high-chip-rate fragments in media presentation description (Media Presentation Description, MPD) to request the server, so that the server may provide high-chip-rate video experience for the user; in the case of insufficient bandwidth resources, the user will select URLs of low-chip-rate fragments in the MPD to request the server, so that the server may provide low-chip-rate video experience to the user, thus ensuring the smoothness of real-time experience of the user.
The Progressive Download mode refers to that the user obtains the media file from the server through the HTTP protocol, and part of the media file may be played while the rest of the media file is downloaded after a short start cache time. In this mode, the terminal may select a high-definition media file to request the server based on the maximum rate allowed by itself and the network, and the chip rate of the requested file is constant. Therefore, the user may be provided with a high-quality video content.
After the MPD is expanded, the URL address information downloaded in the Progressive Download mode is added in the MPD content information.
However, when the Adaptive Streaming mode is adopted to download the media file, the content of the downloaded media file will be adjusted according to the conditions of the network resources, if the network resources are insufficient, then the video quality will be reduced, moreover, the Adaptive Streaming mode consistently occupies certain bandwidth resources, when the user hopes to download a video with higher quality for viewing, for operators, this scenario is a waste of the bandwidth resources; when the Progressive Download mode is adopted to download the media file, since no certain bandwidth resource is consistently occupied, in the case of insufficient network resources, the video content is interrupted to fail to provide a smooth media resource.